Infectious Disease Scenarios Flashcards
A 33yo woman presents with an itchy vaginal d/c fro the past 2 days. She has been healthy other than a recent sinus infection for which she took a 10 day course of amoxicillin. Her husband is her only sexual partner and he has no symptoms. On exam, the vulva is noted to be slightly erythematous and swollen with some evidence of excoriation. D/c is white and clumpy. Provided the most likely dx is confirmed on microscopy, the first line therapy is:
a) metronidazole 500mg i po bid for 1 week
b) metronidazole 500mg 4 tabs po at HS x 1 night
c) fluconazole 150 mg i po x 1 day
d) recephin 250 mg IM x 1 dose
c: The clinical presentation is consistent with vulvovaginal candidiasis. The recent oral abx use increased her risk for developing the infection. The white clumpy d/c and relatively benign bimanual examination support the dx, which is confirmed by 10% KOH wet mount of the secretions. Tx for an uncomplicated case may include topical or oral antifungals. Oral fluconazole in the one dose regimen is effective, convenient, and likely to increase compliance. The metronidazole regimens are appropriate for bacterial vaginosis and trichomoniasis. Rocephin is an option for gonococcal infection and would likely worsen the candidiasis.
An HIV positive patient with CD4 count for 225 cells/mL should receive prophylaxis for which of the following opportunistic infection?
a) Pneumocystis jiroveci
b) toxoplasmosis
c) candidiasis
d) Mycobacterium avium
e) cytomegalovirus
a: Prophylaxis against opportunistic infections is an important part of management in the HIV-infected pt. Prophylaxis for PCP with trimethoprim sulfamethoxazole is the only one in the list indicated when the CD4 count is >200.
A 55yo man with a hx of chronic renal failure, 6 months status/post RENAL TRANSPLANT, presents with CP, productive cough, and low grade fever. He reports generalized malaise as well. Current meds include only those related to his transplant. He has no known allergies. Exam reveals temp 12, unremarkable HEENT, and few crackles anteriorly in upper right lung field. CXR reveals a SOLITARY NODULE in the RUL. The most likely etiology for his symptoms is
a) Streptococcus pneumoniae
b) Pneumocystitis jiroveci
c) cryptococcosis
d) Candida
e) influenza A
c: Cryptococcal species are opportunistic organisms responsible for infections in immune-compromised hosts. With the rise of HIV infections in the past few decades in the US, cryptococcosis is becoming increasingly prevalent. IT is also common infection in those who have undergone organ TRANSPLANTATION. The two most common areas for infection are the lungs and CNS. Pulmonary involvement includes fever, productive cough, chest discomfort, and weight loss. Pleural effusions, lymphadenopathy, and solitary or multiple nodules can all be seen on CXR. CNS manifestations include meningitis symptoms. Dx is confirmed with INDIA INK PREP of CSF showing yeast or histologic stains of tissue from the involved organs. Tx with oral or parenteral anti fungal agents
Which of the following infectious agents is most likely to be found in a rural Kentucky farmer or someone who is responsible for clearing bats out of the local caverns before the tourist season begins?
a) cryptococcosis
b) histoplasmosis
c) psittacosis
d) Candidal species
b: Histoplasmosis is found thought the US with greater concentration in the Ohio and Mississippi river valleys. It is found in soil, particularly in areas with lg quantities of decaying wood or bird droppings. Bats also carry histoplasma. Cryptococcus is most likely in people exposed to pigeons and is also found in soil enriched by bird droppings or in cockroach-infested environments.
An 8yo girl is brought into the ED with abdominal cramps, nausea, and vomiting since early this morning. She has had two loose stools but denies melana or hematochezia. She has had a low grade fever. In the past hour, her vision as become blurry and she feels increasingly weak. Her mother has had similar symptoms. 24H dietary recall includes only chicken broth today. Last night for dinner, they had meatloaf (fully cooked), potatoes, and green beans. Her mother CANS ALL THEIR VEGETABLES. Exam reveals a temp of 99, clear lungs, and mildly tachycardia hear with no murmurs. Neurologic exam is significant for decreased visual acuity and decreased motor strength (2/5) in upper and lower extremities. The most likely etiology is:
a) enterotoxic E coli
b) cholera species
c) pinworms
d) Clostridium botulinum
d: Clostridium botulinum produces a neurotoxin that can lead to life-threatening illness including respiratory paralysis. Botulism infection is caused by the spore-forming bacteria that lives in the soil and can be foodborne. In the latter case, home-canned foods are often the cause. After a 12H to 3 day incubation period, botulism begins with classic symptoms of abdominal pain, nausea, vomiting, and mild diarrhea and, if unchecked, evolves into progressive neurologic disorder marked by double vision, motor weakness, and ptosis. Respiratory muscle involvement may occur and result in death. Because of the virulence of the neurotoxin it has been used as an agent of bioterrorism. Cholera and enterotoxigenic E coli cause a food borne diarrheal illness that can result in significant morbidity and mortality, but DO NOT have neurologic manifestations. Pinworms infection is usually found among younger children, is marked by severe anal itching, and fecal-oral transmission.
A 21yo bodybuilder presents with complaints of diarrhea, cramps, and low grade fever x24H. He has been training for a competition, eating lg amounts of protein, and supplementing with shakes made with raw eggs. He reports three loose stools today, but says he has been able to eat and take fluids. He only cam in today because the BLOOD in the toilet alarmed him On exam, he is noted to be a well-muscled man in no apparent distress; lungs and heart unremarkable; abdomen, mild hyperactive bowel sounds with no tenderness or organomegaly; no evidence of hemorrhoid or fissure, no masses, and no stool present for hem occult. The most appropriate first line tx is:
a) ciprofloxacin
b) metronidazole
c) trimethoprim sulfamethoxazole
d) fluconazole
e) supportive care
e: Salmonella infection, caused by consuming raw eggs, is the most likely dx in this case. The most common salmonella serotypes in the US include Typhimurium and Enteritidis. Infection is characterized by fever, abdominal cramps, diarrhea (and sometimes blood) following a 12-72 H incubation period. Most cases are self-limited, resolving within a week. For this reason, they are usually managed with supportive care only! In the rare cases in which sepsis occurs, the pt should be hospitalized and tx with Bactrim or a FQ.
Which of the following food borne infectious illnesses may cause seizures in pediatric patients?
a) salmonellosis
b) shigellosis
c) cholera
d) campylobacter
b: Shigella, salmonella, and campylobacter infections all include fever, cramping, and bloody diarrhea but only shigella is known to progress to seizures in children. Salmonella is generally self-limited and resolves with supportive care. Campylobacter may cause an overwhelming sepsis in the immune-comprosied. Cholera is a waterborne infection with lg volume diarrhea and associated dehydration and also has the potential to result in sepsis.
Which of the following food borne illnesses is most likely to be acquired through eating raw oysters?
a) salmonellosis
b) shigellosis
c) cholera
d) giardia
e) hookworms
c: Cholera infection is most often caused by Vibrio cholerae, Vibrio vulnificus, or Vibrio parahaemolyticus. Although cholera infection can be transmitted through wounds, the most often reported cause is eating undercooked shellfish. The clinical picture most often includes a watery diarrhea that can lead to dehydration. In the immune compromised host, overwhelming sepsis is possible. It is most often treated with doxycycline plus a third generation cephalosporin or by a FQ alone. Salmonella infection is associated with consumption of raw eggs and undercooked chicken or beef. Shigella is transmitted via fecal-oral route, often because of poor hygiene. Giardia is waterborne and hookworms are found in soil.
A 3yo African immigrant woman is brought to the ED with congestion and sore throat. Her family has been in the US for only 1 month. They were “rescued” from refugee camp by a private relief organization. This is her first medical evaluation. On exam, she is noted to have a low grade fever; tympanic membranes are pearly gray without injection or visible air fluid levels. Throat is ERYTHEMATOUS WITH ENLARGED TONSILS COVERED BY A GRAYISH MEMBRANE. Tonsillar nodes are tender. Lungs are clear. Rapid strep screen is negative. The most likely etiologic agent is:
a) Bordetella pertussis
b) Corynebacterium diphtheriae
c) Streptococcal pyogenes
d) Hemophilus influenza
b: The clues to the etiology of this presentation include the GRAY psuedomembranes on the tonsils and lack of medical care resulting in the missed childhood vaccines. Corynebacterium diphtheriae causes a respiratory and posterior pharyngeal infection with little likelihood of sepsis. However, the case fatality rate is high with mortality from neurologic impairment increasing the longer treatment is delayed. Because it released a toxin into the local tissue in the throat, a tough GRAY colored pseudomembrane over the tonsils is the classic clinical finding. Although culture on social media of a specimen collected from beneath the membrane confirms the dx, therapy should be started based on clinical suspicion and includes parenteral penicillin or erythromycin. Vaccination with diphtheria toxin is preventative.
The most common cause of fever of unknown origin, with other symptoms including nausea, vomiting, abdominal pain, myalgia, and arthralgia, severe enough to require hospitalization in the returning traveler is:
a) malaria
b) dengue
c) enteric fever
d) leptospirosis
a: Malaria is the MC cause of fever and hospitalization in travelers returning to the US. Those with no hx of exposure develop the most severe cases. There are four species of Plasmodium casing human infection in the US, with P. falciparum and P. vivid being the most common and P. falciparum causing the most severe dz. Most US travelers contract Malaria in west Africa. P falciparum has a shorter incubation period (up to 30 days). Symptoms are variable but may include fever, nausea, vomiting, abdominal pain, myalgia and arthrlagias. On physical exam, some will have increased HR with decreased BP progressing to changes in mental status. Confirmation of malaria is obtained with Giemsa-stained peripheral smears. Tx includes oral quinine for less severe cases or IV quinine for the more severe. Doxycycline or clindamycin are added to either regimen. Px for malaria for travelers to endemic areas is very effective.
A 16yo boy presents to the office with complaints of rash, low-grade fever, HA, and malaise. Symptoms began yesterday after he spent most of his free time in the past 4 days deer hunting in the woods around his house. He reports that he does check himself for ticks every night. He often finds them but has not noticed any this season that were latched onto his skin. ON exam, his temp is 99.9, his HEENT is unremarkable, and he has 1 to 2 mm RED MACULES OVER HIS WRISTS AND ANKLES with remainder of skin clear. The most likely dx is:
a) lyme disease
b) Rocky Mountain Spotted Fever
c) ehrlichiosis
d) Q fever
b: Rocky Mountain spotted fever is a rickettsial infection caused by Ricketsia ricketsii. The organism is transmitted to humans through the bite of the dog tick and is more common among those who spend time outdoors in wooded area. The illness begins with generalized symptoms of fever, HA, nausea, vomiting, malaise, and myalgias. The rash of rocky mountain spotted fever begins as a macular rash and progresses to non blanching petechiae. The rash begins over the wrists and ankles and progresses to the arms, legs, and trunk. Untreated, it can progress to respiratory failure and/or CNS involvement. DOC is doxycycline. Lyme disease is distinguished from rocky mountain spotted fever by the pattern of the rash. Lyme disease is characterized by the classic erythema migrans rash, usually on the trunk.
Which of the following causes an opportunistic infection in those with HIV when the CD4 count drops below 100 and is associated with esophagitis, encephalitis, and peripheral neuropathies and has prophylaxis available for retinitis when CD4 count drops below 50?
a) Cytomegalovirus
b) Toxoplasma gondii
c) Mycobacterium avium
d) Pneumocystis jiroveci
Cytomegalovirus is an opportunistic agent that causes clinical symptoms in a number of systems. CMV esophageal ulcers can occur when CD4 count drops below 100 and usually responds well to IV ganciclovir. CMV can also cause encephalitis with altered level of consciousness. In addition to CNS impairment, CMV infection can lead to a peripheral polyradiuclopathy. The retinitis associated with CMV usually does not develop until CD4 count drops below 50. Prophylaxis is available, but the benefits must outweigh the risks of the medicine. Toxoplasmosis prophylaxis begins when CD4 count drop below 100. Pneumocystitis jiroveci primary causes pneumonia.
Which of the following viral infections often begins with a mild or asymptomatic course in childhood followed by a period of latency in which the virus remains in the trigeminal ganglia and reactivates later?
a) herpes simplex 1 virus
b) parvovirus
c) herpes virus 6
d) varicella zoster
a: The description best fits that of herpes simplex 1. The infection is usually acquired in childhood and may be asymptomatic or severe enough to produce a painful stomatitis. Subsequent outbreaks may be triggered by fever, other infection, stress, or excess sun exposure and are characterized by orolabial outbreak along the trigeminal nerve producing a painful vesicle which over 10-14 days crusts over and resolves. Tx with topical or oral antifungals (acyclovir) shortens the course and lessens the severity if started early. Varicella zoster does have a latency period but often in a spinal nerve or the ophthalmic branch of the trigeminal with rare orolabial involvement.
Which of the following PPD tested patients should receive anti-TB prophylaxis?
a) PPD of 13 mm in a person with no risk factors
b) PPD of 8 mm in a foreign-born person from a country with high prevalence of TB
c) PPD of 3 mm in an HIV positive person
d) PPD of 6 mm in a Native American person
e) PPD of 12 mm in an inmate at a correctional institution
e: Recommendations by the Advisory Committee for the Elimination of TB is indicate that the following high-risk groups should receive preventive chemotherapy if their PPD is >10 mm: 1) Foreign-born persons from high prevalence countries 2) Medically underserved, low income populations, including high-risk racial or ethnic minority populations. 3) residents and employees of facilities for long-term care 4) Injection drug users who are HIV negative 5) children younger than 4 or children and adolescents in contact with high risk adults 6) lab employees working in mycobacteriology
A pt with no hx of tx for primary syphilis presents with symptoms and signs consistent with secondary syphilis. The most common sign of secondary syphilis is:
a) generalized lymphadenopathy
b) aseptic meningitis
c) alopecia
d) generalized maculopapular rash
e) superficial painless gummas
d: Secondary syphilis generally manifest itself a month or two after appearance of the primary chancre. Pts will complain of HA, fever, sore throat, and malaise and will exhibit generalized lymphadenopathy along with a maculopapular rash that begins at the sides of the trunk and later spreads over the rest of the body. The skin lesions may coalesce in warm moist areas. Skin and mucosal lesions are the most common sites of secondary syphilis.
